Natural hazards Flashcards
what is a natural hazard
events that are perceived to be a threat to people, the built environment and the natural environment.
geophysical
driven by the earth’s own internal energy sources, for example, plate tectonics, volcanoes, seismic activity.
hydrological
driven by water bodies, mainly the oceans, for example, floods, storm surges, tsunamis.
atmospheric
driven by processes at work in the atmosphere, for example, tropical storms, droughts.
why do we avoid looking at the frequency and magnitude?
- Damage occurs almost immediately or after hazard occurs.
- do not choose to be exposed to the impacts.
- clear origins of courses
- distinctive effects e.g. collapse of the built environment and infrastructure.
The UN’s definition of disaster
- 10+ people killed
- 100+ people affected
- a state of emergency
- international assistance called for
1990 Swiss Re insurance
Defined disaster as an event where at least 20 people died, or injured + damage of $16M.
risk
The chance of loss from an event that cannot be entirely controlled
vulnerability
the quality or state of being exposed to the possibility of being attacked or harmed, either physically or emotionally.
hazard
A potentially damaging physical event, that may cause – loss of life or injury
- property damage
- social/economic disruption
- environmental degradation
capacity
a combination of all strengths and resources available within a community, society or organisation that can reduce the level of risk, or effects of a disaster.
how is capacity measured?
R = H × V
c
Risk (R) = Frequency of hazard (H) × Vulnerability (V)
÷ capacity to cope
what is the effect of increasing hazards?
as the risk of disaster grows as global hazards and people’s vulnerability increases, while their capacity to cope increases.
Perception
this is the way in which someone understands or interprets a hazard. People tend to respond to hazard depending on their understanding and interpretation.
Fatalism
An optimistic or accepting approach, while people believe that hazards are part of life or ‘acts of god’.
domination
this is the perspective suggests that hazards are predictable and that they can be better understood by scientific research.
Adaptation
this perspective takes view that hazards are influenced by natural and human events and so we change our lives to reduce impacts
what makes people vulnerable?
- food stocks destroyed as a result of hazard event: famine.
- water contaminated by power plants or debris from infrastructure.
- corrupt government: Laissez-faire approach or use up the money themselves.
what types of hazards can be prevented?
- Avalanches: slopes to offset/control in order to prevent a larger avalanche.
- flooding: prevented = engineering solutions
- volcanic eruptions - satellite images
which types pf hazards cannot be predicted?
- Earthquakes - can figure out areas of risk though.
- Tornadoes.
- Tsunamis - cannot be adapted.
how can the built environment be salvaged?
- earthquake-proof buildings
- raising houses on stilts in flood areas
- Flood defences
- retrofitting existing structures to improve their defences
- hazards cannot be adapted in any way by people but can dilute impact where it helps.
can all events be predicted to the same degree?
nope, but satellite images and radar technology helps to predict large-scale extreme climatic events. volcanoes can be closely monitored and some predictability can be gained.
can earthquakes be predicted?
NOPEEE - devasting effects over large areas due to not knowing the signs.
how will recognizing warning signs help?
key to prediction + recognising warning signs = actions.
then only long term prep can help them.
who are most affected by hazards?
- poor
- young
- old
factors of vulnerability
- Age
- education
- development
- communication technology
what can help reduce factors of vulnerability of the population?
- planning laws
- building design
- precision technology and research
- emergency service provision
- aid provision
- communication + education
examples of adapting to hazards
- not allowing new building on floodplains
- hurricane evacuation plans and centres
- disaster practice days
- practice + real tornado warning sirens and shelters
what are the factors which affect recovery process for the population?
- speed of response from authorities
- level of economic development in the area
- extent of damage done to the infrastructure of their lives
- morale of the community
- types of aid, short and long term
- collaborative between governments and aid agencies
MEDCs
More Economically Developed Countries
LEDCs
Less Economically Developed Countries
how can the population help?
Individual = effect on one person Authority = millions affected
Insurance in MEDCs
💰 to an insurance company based on the likelihood of damage. some properties are given HIGH insurance due to high risk. some have such a high risk NO insurance is paid.
positive response to modifying loss
- find a solution
- control the effects
- acceptance
negative responses to modifying loss
- deny its existence
- deny its recurrence
- blame others
- fatalism: “it’s happening anyway, what’s the point of doing anything, it is all in gods hands” (acceptance of disaster as it is)
influence/social pressure
pressure from community leaders + social media = strong influence on peoples choices when it comes to their own safety.
Duration
- the length of time that a hazard lasts for
- the longer the hazard the more severe it is likely to be
- e.g. an earthquake that lasts one minute will have a much more severe impact than an earthquake that lasts
2 seconds.
Magnitude
The strength of a hazard
give an example of a measure for the strength of a hazard
- Richter scale - earthquakes
- volcanic explosivity index (VEI)
predictability
this is the likelihood of being able to predict a hazard.
give an example of hazards that can be predicted
- volcanoes give warning signs
- tropical storms can be tracked with satellites
which hazards are hard to predict?
earthquakes
true/false: generally speaking hazards that hit with no warning are going to be much more serious
true
regularity
if hazards happen often and in quick succession e.g earthquakes and then aftershocks
frequency
the interval of hazards of certain sizes e.g. an earthquake that is 8.0 happens once a year but you can have earthquakes that are 3.0/4.0 that occur daily. less strength but much more frequent earthquakes have the biggest impact
speed of onset
the speed at which the hazard occurs e.g an earthquake can happen immediately and it would be hard to cope with impacts of it but if it is a hazard like a drought you can deal with the impacts as it happens.
spatial concentration
hazards that are located in known areas are better to prepare for e.g. earthquakes tend to occur along plate boundaries or tropical storms are known to occur in coastal areas.
Areal extent
if hazard covers a large area
- e.g. a drought affecting the whole of east Africa
- that is much worse than a flood hitting just one village
number of hazards
locations that could usually be hit with multiple hazards e.g. hazard hotspots such as Indonesia can be hit by earthquakes, volcanoes, landslides and flooding simultaneously.
